Porous web impregnation employing capillary tubes and grooves



POROUS WEB IMPREGNATION EMPLOYING CAPILLARY TUBES AND GROOVES J. B. SISSON Filed June 28, 1967.

INVENTOR.

James B. Sisson Mz'm W 2 ATTORNEY 3,536,524 POROUS WEB HMPREGNA'HON EMPLOYING CAPILLARY TUBES AND GROOVES James B. Sisson, Hamilton, Ohio, assignor to The Procter & Gamble Company, Cincinnati, Ohio, a corporation of Ohio Filed June 28, 1967, Ser. No. 649,693 Int. Cl. 1305c 3/18; BMd 1/02 U.S. Cl. 117-120 9 Claims ABSTRACT OF THE DISCLOSURE An apparatus for impregnating a porous moving web with precise amounts of liquid. The porous moving web is led across a plurality of liquid impregnant supplying capillary tube tips disposed in a line transverse to porous web movement, whereby stripes of liquid impregnant are placed on the porous moving Web. The porous moving web with stripes of liquid impregnant thereon can thereafter be passed over a surface having at least one capillary groove normal to the direction of porous web movement to effect even distribution of the previously placed liquid impregnant stripes.

BACKGROUND OF THE INVENTION This invention relates to improvements in apparatus suitable for the impregnation of porous moving webs with liquid impregnants and, more particularly, concerns apparatus for the even application and distribution of small amounts of a liquid impregnant on a porous moving web. Specifically, the invention consists of apparatus, comprising capillary tubes which can be assisted by capillary grooves, both of which capillary tubes and grooves are operatively disposed in a line transverse to the direction of porous web travel, for the placement and spreading of precise amounts of liquid impregnants on a porous moving web.

In the application of small or low level amounts of liquid impregnants to porous webs, particularly paper, non-woven and textile webs, at elevated speeds, i.e., web speeds of over 1,500 feet per minute, certain problems have been encountered in that the available apparatus was useful for saturation or for surface coating, but was not adapted to the low drag distribution of small amounts of liquid on a porous web. Spray methods of liquid placement have not been considered desirable because of attendant overspray and control problems, and the porous bulky nature of many porous webs makes the use of nip and knife coaters undesirable because of web structure deformation or web breakage. Also, in the case of latex impregnation solutions, difificulties in the use of spray methods of liquid impregnant placement were encountered in that high shear in the spray nozzles resulted in partial coagulation of the latex causing spray nozzle plugging.

In developing the aforementioned capillary tube apparatus for the liquid impregnation of a porous moving web, applicant was aware of the method and device which is the subject matter of U8. 1,929,877, issued to Charles Bonamico on Oct. 10, 1933, which method and device comprise a continuous capillary slit placed transversely to and in close proximity with a moving web of the sheet material to be coated. The apparatus disclosed in US. 2,046,596, issued to William A. Zwiebel on July 7, 1936, and that shown in US. 2,598,908, issued to Samuel B. Grimson on July 3, 1952, represent improved devices of the continuous transverse capillary slit type.

Although the transverse capillary slit apparatus proposed heretofore has offered degrees of flexibility in adjustment, it has not proven entirely satisfactory to the 3,536,524 Patented Get. 2?, l9?@ practice of high speed, low level coating because this apparatus had the disadvantage that it otfered no means whereby the amount of a liquid impregnant could be sufficiently reduced Without resorting to a minimum capillary slit dimension which was so small as to induce clogging of the capillary slit. When capillary slit clogging occurred, skips or interruptions constituting a problem in the production of impregnated materials appeared in the impregnation.

SUMMARY OF THE INVENTION Inasmuch as reduced or low level impregnation of porous moving webs with certain liquid impregnating materials such as latexes, perfumes and bactericides was desired, the apparatus of this invention comprising in combination (1) means for guiding and positioning the porous moving web, and (2) supply means terminating in capillary tube tips for said liquid impregnant, which capillary tube tips are positioned operatively with respect to each other and across the nether side of the porous moving web, was developed. The supply means of (2) above can either be operated independently or can be operated in combination with (3) transverse capillary groove means for spreading the liquid impregnant supplied by said capillary tube tips laterally across the porous moving web. Accordingly, it is a principal object of this invention to overcome the aforementioned disadvantages and problems.

Another object of this invention is to provide an impregnating apparatus for a porous moving web whereby the amount of impregnant placed upon the porous moving Web can be easily and effectively adjusted.

Yet another object is to provide an impregnation apparatus for the substantially even placement of small amounts of liquid impregnant over the surface of a porous moving *Web of paper, nonwoven or woven material.

Still another object is to provide an apparatus for the impregnation of a porous moving web whereby amounts of impregnant less than that equivalent to the ultimate absorptive capacity of the porous moving web can be distributed over the surface of said web in a substantially even manner.

A still further object of this invention is to provide apparatus adapted to the impregnation of relatively weak paper webs which tend to lose cohesive strength upon impregnation.

BRIEF DESCRIPTION OF THE DRAWING apparatus of the present invention mounted in operative relation with respect to the nether surface of a porous moving web.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In describing the preferred embodiment of the invention illustrated by the drawing, as well as the variations thereof described hereinbelow, specific terminology will be resorted to for the sake of clarity. It is not intended, however, to be limited to the specific terms so selected, and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose.

Referring to the specific embodiment of the invention selected for illustration in the drawing, number 11 designates generally an apparatus for the liquid impregnation of a porous moving web 12. Porous moving web 12 can issue from a roll, not shown, and can be rewound on yet another roll, not shown, after liquid impregnation has 3 taken place. Porous moving web 12 can also be impregnated with a selected liquid impregnant at a convenient point in the dry end of a papermaking machine, as a part of an initial papermaking operation.

One object of the present invention, hereinabove stated, is to provide for the low level impregnation of a porous moving web, which porous moving web loses tensile strength upon impregnation, in such a manner that the minimum machine direction pull or drag is applied to the porous moving web during its impregnated and weakened condition. This object is accomplished by apparatus 11 in that it provides for a minimal amount of drag on porous moving web 12.

Apparatus 11 includes a lower guide bar 13 and an upper guide bar 14 which urges porous moving web 12 into operative juxtaposition with the ends of capillary tubes 15 and specifically with capillary tube tips 15a, mounted on and connected into manifold box 20. Although apparatus 11 is illustrated with a single row of capillary tubes 15, it will be understood that a plurality of rows of capillary tubes 15 can be mounted on manifold box 20, if required. Apparatus 11 also includes means for spreading liquid impregnant on porous moving Web 12, the specific illustrative example of which is capillary groove bar 16, which capillary groove bar 16 has capillary grooves 22 on the top surface thereof which are placed transversely to the travel direction of the porous moving web 12. Porous moving web 12 finally passes under capillary groove hold down bar 17 and under infrared heating unit 18. The base of apparatus 11 is fixed base support 19. The supports of lower guide bar 13, upper guide bar 14 and capillary groove hold down bar 17 are partially cut away to facilitate illustration, as is porous moving web 12.

Lower guide bar 13 and upper guide bar 14 are adjustably mounted on fixed base support 19 and are verticallly adjustable to position porous moving web 12 in operative relationship with capillary tube tips 15a. Lower guide bar 13 and upper guide bar 14 can consist of rollers which can be mounted on ball bearings to reduce drag on porous moving web 12. In roller form, lower guide bar 13 and upper guide bar 14 can further be made of a light metal, for example aluminum, to minimize roller torque and thus reduce tensile forces in porous moving web 12. In other embodiments of this invention, lower guide bar 13 and upper guide bar 14 can either be the bowed Web spreading bars, conventional in the papermaking industry, or they can be straight bars and motor driven rolls. Lower guide bar 13 and upper guide bar 14 serve as means of insuring the flatness of porous moving Web 12 and the substantially constant operative relationship thereof with capillary tube tips 15a. Although lower guide bar 13 and upper guide bar 14 are the selected means for producing this operative relationship with capillary tube tips 15a for purposes of illustration in the preferred embodiment of the invention illustrated in the drawing, any means of producing the necessary relationship will be found suitable for use in the practice of the invention.

Capillary tubes 15 are rigidly and substantially vertically mounted on and connecting with the interior of manifold box 20. Manifold box 20 serves to supply liquid impregnant to capillary tubes 15 and can be equipped with precise pressure controls which can consist of a header tank, not shown, supply liquid impregnant to manifold box 20 through supply header 24. Alternatively, the pressure in manifold box 20 can be controlled by a pressure regulator mounted in supply header 24, not shown, and the present invention includes systems wherein each of capillary tubes 15 is connected to a separate supply header 24 and regulated to a different pressure or wherein selected groups of capillary tubes 15 are run at different set pressures across the width or deckle of porous moving web 12. The internal diameter of capillary tubes 15 is governed to some degree by the type of liquid impregnant to be placed on porous moving web 12, but capillary tubes with internal diameters ranging from about 0.005 inch to about 0.10 inch have been found satisfactory for use. With liquid latex and similar emulsions, capillary tubes having internal diameters of about 0.02 inch to about 0.08 inch are preferable. The smaller internal diameters will be found suitable for use with more fluid solutions, such as perfumes.

Stripes of liquid impregnant 21 placed on porous moving web 12 by capillary tube tips 15a proceed with the travel of porous moving web 12 to the upper surface of capillary groove bar 16. Capillary groove bar 16 comprises a plate having capillary grooves 22 machined, pressed or otherwise formed in the top surface thereof, which capillary grooves 22 are in operative contact with stripes of liquid impregnant 21 and the nether side of porous moving web 12. Capillary grooves 2 are about 0.005 inch to about 0.10 inch in width, preferably about 0.02 inch to about 0.08 inch in width. The ideal width of capillary grooves 22 for a given installation will, however, vary with the liquidity or fiowability of the liquid impregnant. More flowable liquid impregnants favor grooves of lesser width. Capillary grooves 22 can be of V" or U shape. Capillary groove bar 16 can be made of metal, but can also be formed from other materials, for example a quite suitable material is the high molecular Weight, high density polyethylene plastic now available on the market in the form of bars and sheets. To reduce drag on the impregnated and thusly weakened in many instances, while wet, porous moving web 12, the capillary grooves 22 on the top surface of capillary groove bar 16 are placed contiguous one with the other. This placement of capillary grooves 22 lessens the contact area of porous moving web 12 with the actual surface material of capillary groove bar 16. Porous moving web 12 in passing over the upper surface of capillary groove bar 16 is supported in part by a film of the liquid impregnant carried in the capillary grooves 22 and in part by the portions of the top surface of capillary groove bar 16 defining capillary grooves 22.

"Porous moving web 12 can be guided in operative contact with the operative upper surface of capillary groove bar 16 by capillary groove hold down bar 17, but it is also possible to arrange the run of porous moving web 12 so that operative contact with the upper surface of capillary groove bar 16 results. If a capillary groove hold down bar 17 is used, it may assume any of the embodiments described for lower guide bar 13 and upper guide bar 14.

In the particular embodiment of the invention shown in the drawing, there is illustrated a post-coating and spreading means of heating porous moving web 12, infrared heating unit 18. This illustration is intended to convey the information that infrared heating and other posttreatments can be applied to the porous moving web 12 after liquid impregnation to either set, dry, further liquefy, evaporate solvent from, or otherwise enhance porous moving web 12 as a final or intermediate product. Infrared heating unit 18 is mounted on vertically adjustable supports 23 which are supported by fixed base support 19 in such a manner that the height of infrared heating unit 18 above the surface of porous moving web 12 can be regulated. The effect of infrared heating unit 18 on porous moving web 12, as well as the effect of other types of drying and heating units, can be further regulated by providing these units with any of the suitable regulatory controls available on the market.

In operation, porous moving web 12 is threaded over lower guide bar 13 and under upper guide bar 14 and thenceforth across the capillary tube tips 15a and the upper surface of capillary groove bar 16. Porous moving web 12 is carried under capillary groove hold down bar 17, if this device is used. Alternatively, the use of capillary groove hold down bar 17 can be dispensed with in favor of leading porous moving web 12 directly from capillary groove bar 16 to a suitably positioned set of draw rolls, turn rolls or rewind rolls, all of which commonly and conventionally used rolls are not shown. Upper guide bar 14 is vertically positioned with respect to the upper grooved surface of capillary groove bar 16 so that porous moving web 12 is placed in operative position across capillary tube tips a.

Porous moving web 12 then passes in operative position above capillary tube tips 15a; by operative position it is meant that the nether side of porous moving web 12 is sufficiently close to capillary tube tips 15a so that liquid impregnant issuing from capillary tubes 15 is picked up without gaps, skips or interruptions in the lines or stripes placed on the nether side of porous moving web 12. Applicant has found that the operative working distance between the nether side of porous moving web 12 and the capillary tube tips 15a can vary up to a maximum of about 0.050 inch, preferably, about 0.020 inch depending on the flow rate and rheology of the liquid impregnant, and in operation the surface of porous moving web 12 can lightly touch the tops of capillary tubes 15. In the embodiment of the present apparatus illustrated in the drawing, capillary tubes 15 are about /8 of an inch long and are spaced about A of an inch apart on their centers. These dimensions are not intended to limit the present disclosure, but are given as one example of actual dimensions for a working device. The spacing of capillary tubes 15 in a given installation is a function of web absorbency, internal capillary tube diameter and the desired quantity level of liquid impregnant. Capillary tube 15 spacings of about /8 inch to about inch on centers will be found suitable for various installations, with spacings of about A inch to about M; inch preferable in most installations. The closer spacings of capillary tubes 15 may be achieved by staggering multiple rows of capillary tubes 15 so that the projected spacing normal to the travel of porous moving web 12 is the effective spacing.

The internal diameter of the capillary tubes 15 in the embodiment of the apparatus illustrated is about 0.06 inch; but this dimension will vary with the surface tension of the liquid impregnant and the impregnant application rate for which a particular apparatus is designed as discussed above, although it is believed desirable that the internal diameter of capillary tubes 15 should not be less than about 0.020 inch for use with latex impregnation solutions, due to flow stoppage considerations.

After the stripes of liquid impregnant 21 are placed upon the nether side of porous moving web 12 by capillary tube tips 15a, the porous moving web 12 passes in machine direction over the surface of capillary groove bar 16. Porous moving web 12 may be urged downward to be in contact with the grooved surface of capillary groove bar 16 by capillary groove hold down bar 17, and this arrangement is shown in the specific embodiment of the apparatus illustrated in the drawing. Capillary groove bar 16 serves the purpose of spreading, over substantially the entire nether surface of porous moving web 12, the liquid impregnant which arrives on its surface as stripes of liquid impregnant 21. From the surface of capillary groove bar 16, porous moving web 12 passes under capillary groove hold down bar 17 and under infrared heating unit 18, before further conversion, rewind or sheeting operations.

In summation, the drawing illustrates a specific embodiment of apparatus suitable for impregnating or saturating, wherein a porous moving web 12 is driven under tension across the capillary tube tips 15a and the upper surface of capillary groove bar 16. A pair of Web stabilizing and positioning bars, lower guide bar 13 and upper guide bar 14, flatten and support the porous moving web 12 so that it passes at a small distance above or in light contact with the capillary tube tips 15a, which are supplied with impregnant from manifold box 20 which is supplied by supply header 24. The porous moving web 12 is in surface tension contact with the liquid impregnant issuing from capillary tube tips 15a, and the nether side of porous moving web 12 acquires stripes of liquid impregnant 21. On passing over the upper surface of capillary groove bar 16 the liquid impregnant immediately fills and is spread laterally, that is transversely to the machine direction travel of porous moving web 12, by capillary grooves 22. The rate of liquid impregnant application is readily controlled by adjustment of the supply pressure on supply header 24, and either with certain liquid impregnants or in instances where a less perfect distribution of the liquid impregnant can be tolerated, it is possible to dispense with the use of capillary groove bar 16 and use capillary tube tips 1511 together with natural absorption of the stripes of liquid impregnant 21 by porous moving web 12 to effect liquid impregnation distribution.

The advantages of apparatus 11 for impregnation are numerous, and it is especially adapted for use in the low drag impregnation of a tissue-weight porous moving Web 12 with amounts of liquid impregnant less than those amounts represented by or equivalent to the ultimate absorptive capacity of a given porous web. Another advantage of apparatus 11 is that it affords easy adjustability by means of the supply pressure applied to manifold box 20 through supply header 24. Still another advantage of the type of apparatus 11 is that groups of capillary tubes 15 can be partitioned off and fed with liquid impregnant by means of separate supply headers 24 and manifold boxes 20*, so that a liquid impregnant profile or level may be established across the width or deckle of porous moving web 12, which liquid impregnant profile or level can be adjusted or maintained as for example humidity, or other absorptive conditions in the porous moving web require such adjustment.

It is to be understood that the form of the invention illustrated in the drawing and described herein is to be taken as a preferred embodiment. Various changes may be made in the shape, size and arrangement of the various parts. For example, equivalent elements may be substituted for those illustrated and described herein, parts may be reversed, and certain features of the invention may be utilized independently of the use of other features, all without departing from the spirit or scope of the invention as defined in the subjoined claims. As a specific example of such substitution, the manifold box 20 may take a circular shape, as by fabrication from a pipe, and such manifold box 20 may be fed by a plurality of supply headers 24 in the manner conventionally used to feed papermaking furnish to a pressure headbox for use on a Fourdinier machine.

Apparatus constructed in accordance with this invention can be utilized for the coating of tissue paper, toweling, nonwovens and woven fabrics; accordingly, it is to be understood that the term porous moving web as used herein encompasses any porous paper, nonwoven or fabric material which may benefit from a liquid impregnation performed with the above described apparatus.

Having thus defined and described the invention, what is claimed is:

1. An apparatus for use in applying a liquid impregnant to a porous moving web, which apparatus comprises in combination:

(1) means for guiding and positioning the porous moving web, and

(2) supply means terminating in a plurality of distinct capillary tube tips for the said liquid impregnant, which capillary tube tips are positioned operatively with respect to each other and transversely across the nether side of the porous moving web.

2. An apparatus for use in applying a liquid impregnant to a porous moving web as claimed in claim 1 wherein the internal diameter of the capillary tube tips is about 0.005 inch to about 0.10 inch and said capillary tube tips are positioned transversely across the porous moving web at a distance of about inch to about ,6 inch from each other.

7 in applying a liquid impregweb, which apparatus com- 3. An apparatus for use nant to a porous moving prises in combination:

(1) means for guiding moving web,

(2) supply means terminating in a plurality of distinct capillary tube tips for said liquid impregnant, which capillary tube tips are positioned operatively with respect to each other and transversely across the nether side of the porous moving web, and

(3) transverse capillary groove means for spreading the liquid impregnant supplied by said capillary tube tips laterally across the porous moving web.

4. An apparatus for use in applying a liquid impregnant to a porous moving web as claimed in claim 3 wherein the internal diameter of the capillary tube tips is about 0.005 inch to about 0.10 inch, said capillary tube tips are positioned transversely acorss the porous moving web at a distance of about /8 inch to about A inch from each other, and the transverse capillary groove means for spreading said liquid impregnana has capillary grooves with a least dimension of about 0.005 inch to about 0.10 inch.

5. An apparatus for use in applying a liquid impregnant to a porous moving web as claimed in claim 3 wherein the internal diameter of the capillary tube tips is about 0.02 inch to about 0.08 inch, said capillary tube tips are positioned transversely across the porous web at a distance of about A: inch to about inch from each other, and the transverse capillary groove means for spreading said liquid impregnant has capillary grooves with a least dimenion of about 0.02 inch to about 0.08 inch.

6. A process for impregnating a porous moving web with a liquid impregnant, which process comprises the steps of (1) supporting said porous moving web in an operative position above a plurality of spaced capillary tube tips, and

(2) passing the porous moving web a maximum distance of about 0.05 inch above said capillary tube tips, but no so far as to cause an interruption in the and positioning the porous L) liquid impregnant supply, while supplying liquid impregnant transfer.

7. A process for impregnating a porous moving web with a liquid impregnant as claimed in claim 6 wherein the porous moving web is passed a maximum distance of about 0.02 inch above said capillary tube tips, but sufficiently close to said capillary tube tips to insure impregnant transfer.

8. A process for impregnating a porous moving web with a liquid impregnant, which process comprises the steps of:

(1) supporting said porous moving web in an operative position above a plurality of spaced capillary tube tips,

(2) passing the porous moving web a maximum distance of about 0.05 inch above said capillary tube tips, but not so far as to cause an interruption in the liquid impregnant supply, while supplying liquid impregnant to said capillary tube tips, and

(3) spreading the liquid impregnant applied in Step 2 laterally across the porous moving web by means of capillary grooves.

9. A process for impregnating a porous moving web with a liquid impregnant as claimed in claim 8 wherein the porous moving web is passed over said capillary tube tips at a maximum distance of 0.02 inch, but not so far as to cause an interruption in the liquid impregnant supply, while supplying liquid impregnant to said capillary tube tips.

References Cited UNITED STATES PATENTS 1,910,670 5/1933 Blaser. 2,066,780 1/1937 Holt 11764 2,961,336 11/1960 Uhleen 117120 X ALFRED L. LEAVITT, Primary Examiner C. K. WEIFFENBACH, Assistant Examiner US. Cl. X.R.

mg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3.536.5 4 Dated October 27, 1970 Inventm-(J) James B. Sisson It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

q Column 3, line 65, "supply" should read --supplying--.

Column 4, line 17, "grooves 2 should read --grooves 22--.

Column 6, line 49, "Fourdinier" should read -Fourdrinier--.

' Column 7, line 18, "acorss" should read --across--.

Column 7, line 21, "impregnana" should read --impregnant--.

Column 7, line 28, "porous web" should read --porous moving web--.

Column 7, line 42, "no" should read --not--.

Column 8, lines 1 and 2, "impregnant transfer. should read --impregnant to said capillary tube Column 8, lines 7 and 8, "insure impregnant" should read -;-insure liquid impregnant--.

JIGNED W:

Arrest: E- SOITJXLEK, .m

domissionar of Patents EdwardMFletchenk.

Attesting Officer 

